So who's the audience on these Batteriser videos? 99.99% of Dave's audience already understands what he's talking about.
If Dave's trying to deter people from investing in this concept or buying this stuff, his approach probably isn't the best. Non-electronic people are going to spend thirty seconds and leave just feeling uncertain... at best.
Batteriser has posted enough content that it could be used as more effective ammo against them.
For example:
1. Point out that they were claiming +800%, now just +80%. PCworld, CNN, etc all still have those +800% claims even though their website and CF page no longer does.
2. Take the Apple keyboard and repeat their results. Sure the meter would go up to 100% with a SMPS, but you can show that you'll only get maybe 1% more life... not +80%.
3. Illustrate that such a device is only useful when product design is poor. Buy a Garman GPS and repeat the latest test with an ultra efficient SMPS. If it does work as they describe, you could show how it is NOT well designed. Then you could show the other twenty products on their website DON'T give similar results. i.e. Xbox controller, RC cars, TV remote, Thomas the train toy, Sony BlueTooth speaker, flashlight, monkey, etc.
4. They installed the Batteriser's on fresh batteries with the Garman GPS test. How about doing the same thing with low current devices to show that, due to the quiescent current of a SMPS, the battery's last less time depending on how much current is being drawn.
I think those real-world examples would better illustrate the point. Especially item #3, in which the tear-down would be more applicable to your core audience. Title it "How not to design a battery powered product".
tldr?
This thing only appears useful when a product draws a very high current pulse at very low duty cycles with a poorly designed low battery level notification. So basically why not just hook a SMPS up to the other 99% of modern devices to show typical experiences?